Born at Barksdale AFB in Louisiana, Earls originally trained as an architect, earning a bachelor's degree in Fine Arts. After sixteen years as an architectural designer, Earls moved to California to work as art director on a friend's computer games company. Unfortunately, the company failed not long after Earls arrived, leaving him searching for a position without a large number of contacts. Earls eventually ended up at Babylonian Productions, where he worked as a set and concept designer, and visual effects art director on Babylon 5 (starring Mary Kay Adams, Andreas Katsulas, Bill Mumy, Tracy Scoggins, Patricia Tallman, and Walter Koenig) and its sequel series, Crusade. From there, Earls was brought on board Star Trek: Voyager by Richard James and Louise Dorton.

In addition to his work on Voyager and Babylon 5, Earls was also set designer for such TV shows as V.I.P., Judging Amy and Resurrection Blvd. and was a visual consultant on Brannon Braga's shot-lived CBS series Threshold, starring Brent Spiner.

Earls has designed sets for several major motion pictures. For Paramount Pictures, he worked on 2003's The Italian Job and was senior lead set designer on 2006's Mission: Impossible III. His other film set design credits include Terminator 3: Rise of the Machines (starring David Andrews and Kristanna Loken) and Mr. & Mrs. Smith (which featured Jennifer Morrison and costume designs by Michael Kaplan). He was the lead set designer on the acclaimed science fiction film Serenity (based on the cult TV series Firefly), the 2006 adventure film Poseidon and the hit 2007 action film Live Free or Die Hard (featuring Tim Russ). Earls worked with fellow Voyager set designer Gregory S. Hooper on the latter three films.

He was also an art director on the 2004 remake of Flight of the Phoenix. He more recently designed sets for the musical comedy Walk Hard: The Dewey Cox Story.

Earls considers British designer Derek Meddings to be the biggest influence on his career.